Goblins have a history of pressing malicious and hideous creatures into the service of war. While they deploy Spiderlings to raid vulnerable enemy positions, they handpick the largest of the spiders as cavalry. The strongest among the Goblin Warriors ride giant spiders from Mirkwood into combat with spear and bow. This allows them to move quickly across the battlefield and meet foes such as the riders of Rohan in pitched battle where they would otherwise be crushed under the hooves of the hostile cavalry. Although the spiders are large and strong the riders carry too much equipment for the spiders to easily climb walls, so that duty is left to the Spiderlings and Goblin Warriors. The riders harvest the poison of these massive arachnids for use on their spear tips, making the combination of spider and rider an even more potent threat to strong foes.

Spider Riders in BFME 2 are one of the most deadly troops if you don't know how to handle them. In addition to having poison on their spears, they can also switch to bows, which do a great amount of damage (more than most archers in the game), and are at the same time cavalry.